The present invention relates to a lubricator, and more particularly to a lubricator including a damper serving as a variable restriction mechanism and molded, integrally with a support thereof, of a flexible material, the damper having a groove defined in its base portion for increased flexibility to control the amount of oil mixed in an air flow and increase its durability.
It is well known that a lubricator is generally employed to mix a small amount of oil in compressed air for supplying lubricating oil to a sliding surface in a pneumatically operated device. In the lubricator, the differential pressure produced, by the variable restriction mechanism is utilized to force the lubricating oil upwardly from a case through a siphon tube. The lubricating oil delivered from the case is then drawn through a small hole as atomized droplets into a passage for the compressed air.
One conventional variable restriction mechanism used in the lubricator is illustrated in FIG. 1 of the accompanying drawings. The variable restriction mechanism comprises a resilient tongue-shaped damper 6 disposed in an air passage 4 defined in a lubricator body 2. The damper 6 is sandwiched vertically between bent supports 8a, 8b and fastened thereto by a screw 10. The support 8a has a passage 11 communicating with the air passage 4 and also with a passage 13 defined in a damper holder 12 threaded in the lubricator body 2.
The damper 6 is caused to flex according to the amount of air flowing through the air passage 4 for thereby varying the cross-sectional area of the air passage 4. Part of the air flowing in the air passage 4 is directed through the passages 11, 13 in the direction of the broken-line arrows to impose a force on the oil stored in the lubricator body 2. Therefore, there is produced a differential pressure downstream of the damper 6 which is proportional to the speed of air flow throughout the entire range from a minimum air flow rate to a maximum air flow rate, so that a suitably metered amount of lubricating oil is supplied downstream of the damper 6.
With the prior variable restriction mechanism, the damper 6 is fastened to the supports 8a, 8b by the screw 10. Therefore, where the threaded holes in the supports 8a, 8b or the screw hole in the damper 6 is subjected to a positional error, the height of the damper 6 is varied. As a result, the gap between the wall surface of the air passage 4 and the damper 6 may be increased, with the consequence that the minimum rate of flow of the supplied lubricating oil cannot be lowered. The damper 6 is limited in its flexible length by the supports 8a, 8b. Even when it is flexibly displaced to a maximum extent, it is turned over only to a position in the vicinity of the center of the air passage 4. The damper 6 is therefore liable to oscillate due to a pulsating air flow when the air flows at the maximum rate, resulting in fatigue-induced damage or breakage.